Method and composition for lining a pipe

ABSTRACT

A pipe lining composition and a method for installing the pipe lining composition into a pipeline requiring repair is provided. The lining composition is a layered lining composite formed of alternating plies of felt and carbon fiber strand reinforcing such that layers of carbon fiber reinforcing strands are trapped between layers of felt. Once the composite is laid up the composite is preferably stitched to provide stability and to maintain the layers relative to one another and then formed into a tube. In accordance with the method, the lining tube is then sequentially filled resins of increasing viscosity as it is drawn through rollers in a manner that fully wets out the carbon fiber before it is placed into the pipe to be lined.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/388,256, filed Feb. 18, 2009 which is related to and claims priorityfrom earlier filed U.S. Provisional Patent Application No. 61/036,639,filed Mar. 14, 2009.

BACKGROUND OF THE INVENTION

The present invention generally relates to a method and composition foruse in repairing a pipeline, such as a sewer pipe, by installing a linerinside of the pipeline. More specifically, the invention involves theformation of a reinforced lining sleeve, the method of wetting out thefibers in the reinforcing sleeve and the installation of that liningsleeve on inside walls of the pipeline.

There are numerous pipeline conduits that run underground includingwater lines, sewer pipes, storm water drains, and the like. Over timesuch pipelines generally deteriorate due to ordinary aging, corrosiveaction of the fluids being transported in the line, exposure to unusualenvironmental conditions or for other reasons. As a result, thesepipelines often must be repaired to fix holes, cracks and other defectsthat occur in the line. Despite the cause of the damage, it is importantthat such a damaged pipeline be mended in order to prevent fluid leakageproblems. In some instances the problem may be the result ofinfiltration, where foreign matter leaks through the cracks and into thematerial being carried in the pipeline conduit. For example, rust,asbestos, and other substances may flow from the surrounding undergroundenvironment into the pipeline and contaminate drinking water. In otherinstances the problem is exfiltration, where the fluid that is beingcarried along the pipeline conduit flows outwardly through the cracksleading to a loss of water pressure and other problems.

There are various known methods for renovating existing undergroundpipelines. Many of these methods employ the installation of a lininghose via the use of a calibration hose. For example, U.S. Pat. No.4,714,095 (Müller) discloses a method of salvaging an underground sewerpipe with a lining hose and a calibration hose. The lining hose includesan inner layer that is treated with a first resin and an outer layerthat is not treated with a resin. The lining hose is placed into thepipe conduit. A calibrating hose, having an outer surface thereof coatedwith a resin, is introduced into the interior of the lining and expandedto bring the first and second resins into contact with one another whileexpanding the liner against the interior wall of the pipeline to berepaired. The resins then harden so that the lining hose becomesattached to contact surfaces of the pipeline wall and the calibrationhose.

Similarly, U.S. Pat. No. 4,770,562 (Müller) discloses another method ofsalvaging an underground pipe conduit. A lining hose having an innerlayer that is saturated with a resin and an outer layer that isperforated to form flow-through openings for the resin of the innerlayer is introduced into the pipeline conduit. Then, the lining hose isshaped to conform to the interior surface of the pipeline by introducingan auxiliary hose into the lining hose and injecting fluid into theauxiliary hose. The resins harden to form a lining structure in thepipeline. After the curing step, the auxiliary hose can be kept in thelining hose or removed by ropes or cables.

U.S. Pat. No. 5,653,555 (Catallo) discloses a method of lining a pipeconduit using multiple curing resins. A lining hose that is coated witha high-strength resin is first positioned inside of the pipeline to berepaired. A calibration hose carrying a layer of corrosion-resistantresin is then inverted into the lining hose to expand the lining hoseinto contact with the inside surface of the pipeline. The high-strengthand corrosion-resistant resin layers are then cured by the applicationof a heated fluid to the interior of the calibration hose. The curedlining hose and calibration hose form a rigid self-supporting structureon the interior of the pipeline.

In another Catallo reference, U.S. Pat. No. 5,680,885, a method ofrehabilitating a damaged pipe conduit using a lining hose andcalibration hose is disclosed. The inner layer of the lining hose issoaked with an excess volume of resin while a calibration hose installedtherein contains a resin-absorbent layer. The calibration hose isinstalled by inverting it using pressurized heated water. Afterinversion, the resin-absorbent layer of the calibration hose contactsand adheres to the resin coated layer of the lining hose. Upon curing,the calibration hose becomes an integral part of the liner.

Finally, U.S. Pat. No. 5,706,861 (Wood) discloses a method of lining asection of a pipeline by a “cured in place” system using a lining tubeand inflatable bladder. The lining tube is impregnated with a curablesynthetic resin and is carried into the pipe conduit on an annularinflatable bladder. The bladder is inflated and the lining tube is curedto the pipeline. Then, the bladder is peeled away from the cured liningtube and removed from the pipe conduit by ropes.

Although the above-described conventional methods may be somewhateffective in repairing pipelines, they still suffer from variousproblems. For example, problems arise concerning the inversion of a feltliner because it is relatively delicate and tends to break or rip duringthe inversion process. While the use of reinforcement in the liner isdesirable, due to the manner in which the liners are handled duringinstallation, typical reinforcement fibers that are not fully wetted outhave the tendency to break. Moreover, while carbon fiber is highlydesirable as a reinforcing fiber, it is only effective in multiple pliesand it is extremely difficult to properly wet out.

In view of the foregoing, there is a need for a pipe liner thateffectively incorporates carbon fiber reinforcing. Further, there is aneed for a pipe liner composition and method of installing that pipeliner composition that allows the use of multiple layers of carbon fiberreinforcing while ensuring the proper wet out of the carbon fiber priorto installation thereof. Finally, there is a need for a method ofinstallation of a pipe liner that employs carbon fiber reinforcing thatfacilitates proper wet out of the fibers prior to installation therebygreatly reducing breakage of the fiber reinforcing due to the handlingand installation thereof.

BRIEF SUMMARY OF THE INVENTION

In this regard, the present invention relates to a pipe liningcomposition and a method for installing the pipe lining composition intoa pipeline, such as an underground water pipeline. The composition andinstallation method of the liner of the present invention enables adamaged pipeline to be repaired or salvaged thereby placing it back intocondition for normal use.

The composition of the present invention is a layered lining compositeformed of alternating plies of felt and carbon fiber strand reinforcing.It is preferred that the composite is formed using at least one bottomlayer of felt, at least one inner layer of carbon fiber reinforcingstrands and at least one top layer of felt thereby trapping the carbonfiber reinforcing strands between layers of felt. Further, it ispreferred that the composite may be thicker by alternately addingadditional layers of carbon fiber reinforcing strands and felt toincrease the thickness of the composite using alternate layers. Whileadditional plies may be built up of alternating felt and reinforcingfibers, it is preferred that the top and bottom layers of the compositebe felt. Once the composite is laid up the composite is stitched toprovide stability to the composite maintain the layers relative to oneanother. After stitching, the composite is formed into a tube inpreparation of installing the liner tube as described in detail below.Heretofore, carbon fiber has not been used in such applications becausein its native state it is very brittle and it is difficult to wet outsufficiently.

The lining tube is then filled with a thin resin and drawn throughrollers in a manner that fully wets out the carbon fiber before it isplaced into the pipe to be lined. While the initial wet out resin is oftoo low a viscosity to be used in a structural fashion, it easily wetsout the carbon fiber. Subsequently thicker resins are added and drawnthrough additional rollers until the entire structure is wet out withthe desired resin.

Therefore, it is an object of the present invention to provide a new andnovel lining composite and installation process for lining the interiorsurface of a pipeline to repair and salvage the pipe so that is can beused normally in a leak-free condition. It is another object of theinvention to provide a carbon fiber reinforced structural liningcomposite that effectively seals all cracks and faults in an existingpipeline. It is still a further object of the invention is to provide astructural lining composite that employs carbon fiber that is fullywetted out thereby greatly reducing the breakage that typically occursduring the installation process. Finally, it is an object of theinvention is to provide a method and composite for use in theinstallation of a pipeline liner that improves the overall strength ofthe pipeline.

These together with other objects of the invention, along with variousfeatures of novelty that characterize the invention, are pointed outwith particularity in the claims annexed hereto and forming a part ofthis disclosure. For a better understanding of the invention, itsoperating advantages and the specific objects attained by its uses,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate the best mode presently contemplatedfor carrying out the present invention:

FIG. 1 is a side cross-sectional view of a pipeline within the groundshowing a collapsed liner composition placed in position in the pipelinein accordance with the method of the present invention;

FIG. 2 a is a cross-sectional view through the line 2-2 of FIG. 1showing the layers of the liner composition;

FIG. 2 b is a cross-sectional view through the line 2-2 of FIG. 1showing an alternate arrangement of the layers of the liner composition;

FIG. 3 is a schematic view of the process of wetting out the linercomposition in accordance with the method of the present invention; and

FIG. 4 is a cross-sectional view showing the step of the calibrationhose pressing the liner composition into communication with the innerwall of the pipeline.

DETAILED DESCRIPTION OF THE INVENTION

Now referring to the drawings, the pipe lining composition and a methodfor installing the pipe lining composition of the present invention isshown and generally illustrated. The composition and installation methodof the liner of the present invention enables a damaged pipeline to berepaired or salvaged thereby placing it back into condition for normaluse.

The composition and method of the present invention is used to repair adamaged underground pipeline, such as a water line, so that it can beused in the normal course without undesirable leaks. As can beunderstood, cracks and leaks in a fluid line is undesirable to theassociated pressure drops and flow inefficiencies. With a crackedpipeline, particles commonly break off from the inner surface of thepipeline thereby contaminating the fluid that flows through thepipeline.

Referring first to FIG. 1, a side cross-section view of a typicalpipeline installation is shown. The pipeline or host pipe 6 is installedin the ground 7 where a number of cracks 8 exist representingundesirable leaks. The pipeline 6 includes a horizontal section 6 a anda vertical section 6 b. A common pipeline 6, as shown in FIG. 1, istypically made of concrete. Foreign matter, such as dirt, accumulates onthe inner wall surfaces 9 over time. The debris (not shown) forms hardscale deposits on the wall surfaces, and these scales are difficult toremove. Also, degradation of the pipeline over time causes bits of thepipeline to break off which is exacerbated by cracks therein.

In accordance with the process of the present invention, the insidesurface 9 of the pipeline 6, to be repaired, is preferably firstprepared to remove the aforementioned debris and dirt to ensure a goodbond, as will be described in detail below. Preferably, the inner wallsurfaces 9 of pipeline 6 are cleaned by injecting highly pressurizedwater into the pipeline. The pressurized water stream strikes the insidewalls forcefully and scrubs the walls. For example, the water isprovided at up 30,000 psi to ensure a clean surface. Even higherpressure can be used, if necessary. Known water spraying devices areused for this step of the process. The injected water substantiallyremoves the foreign debris to leave a clean inner wall surface 9remaining. While high-pressure water is preferably used, air or steammay be used instead. Also, additional cleaning agents are not preferablyused but such cleaning agents could be added to the water, air or steamto assist in cleaning depending the application and environment.

After surface cleaning is complete, any standing water left remaining,such as that on the bottom of the pipeline 6, must now be removed. Highpressure air, using known air blowing equipment, is injected into thepipeline to clear it of any remaining cleaning media. In this manner thepipeline 6 is fully prepared and ready to receive a liner as isdescribed in detail below.

Turning to FIG. 2 a, the liner composition 12 of the present inventioncan be seen to be a layered lining composite formed of alternating pliesof felt 14 and carbon fiber strand reinforcing 16. It is preferred thatthe liner composition 12 is formed using at least one bottom layer offelt 14 a, at least one inner layer of carbon fiber reinforcing strands16 and at least one top layer of felt 14 b thereby trapping the carbonfiber reinforcing strands 16 between layers of felt 14. While the termfelt is used herein, the felt layer is preferably any suitable layer ofnon-woven fibrous material. Felt is preferable in that it is a commonlyavailable material that is suitable as a resin-absorbing material. Moreparticularly, polyester-needled felt materials can be used as these feltmaterials have good resin-absorbency properties. Further, as can be seenin FIG. 2 b, if it is preferred that the liner composition 13 may bethicker as by alternately adding additional layers of carbon fiberreinforcing strands 17 and felt 15 to increase the thickness of theliner composition 12 using alternating layers. While additional pliesmay be built up of alternating felt 15 and reinforcing fibers 17, it ispreferred that the top and bottom layers of the liner composition 12 befelt. Once the liner composition 12 is laid up, although not required,it is preferable the liner composition 12 is stitched 18 to providestability to the liner composition 12 and maintain the layers inposition relative to one another. After stitching 18, the linercomposition 12 is formed into a tube in preparation of installing theliner composition 12 in the form of a tube as described in detail below.Heretofore, carbon fiber has not been used in such applications becausein its native state it is very brittle and it is difficult to wet outsufficiently.

Turning to FIG. 3, the liner composition 12 can be seen as it isprepared for installation in accordance with the method of the presentinvention. To overcome the limitation of the breakage of carbon fiber,in accordance with the method of the present invention, after the abovesteps related to the formation of the liner composition 12, the linercomposition 12 is then prepared for installation into the piping bywetting it out with resin. In this process, the leading end of the linercomposition 12 is placed into a press consisting of at least two andmore preferably at least three sets of spaced apart press rollers 20. Athin resin material 22 is injected into the interior of the linercomposition 12 behind the first set of rollers 20 a and a heavier resin24, 26 is injected into the liner composition 12 behind each of thesubsequent sets of rollers 20 b, 20 c. As the liner composition 12 isfirst drawn through the rollers 20 a, the thin resin 22 is urged throughthe layers of felt and carbon fiber initially wetting out the layersthen the second 20 b and third rollers 20 c urge the thicker resin 24,26 into the layered construction of the liner composition 12 effectivelywetting out the entire structure with the desired resin having thedesired consistency. While the first resin 22 may be too thin for thedesired lining process, it serves as an initial agent in starting thewetting out process that allows subsequent wet out by the thickerresins. Once the carbon fiber is fully wetted out in the processdescribed above it can be easily installed into the pipeline to be linedwithout risking the breakage of the carbon fiber reinforcing.

In terms of resins, many different types of curable resins can be usedfor wetting out the liner. While any curable resin may be employed,preferably such a resin will be a thermosetting resin. The resin ispreferably a 100% solid, slow cure, NSF-approved epoxy but also may bean NSF-approved flexible epoxy. The thermosetting resin should have goodadhesive strength and have high strength (for example, high flexmodulus, flex strength, tensile modulus, and tensile strengthproperties.) Similarly, slow-curing resins may be used. For example,polyesters; vinyl esters such as urethane-based vinyl esters, andbisphenol A-fumarate based vinyl esters; and epoxy resins can be used.Epoxy resins are particularly preferred.

As described above relating to FIG. 1 and as is shown in FIG. 4, thewetted out liner composition 12 is then inverted into the pipeline 6 byintroducing a calibration hose into the resin-saturated linercomposition 12 using techniques known in the industry. The calibrationhose can be made from materials such as polyvinyl chloride,polyurethane, polyethylene, polypropylene, polyesters, polyamides, orthe like. The calibration hose is not treated with a curing resin in themethod of this invention. Most importantly, the calibration hose doesnot adhere to the interior of the liner composition 12. The calibrationhose is filled with a pressurized fluid such as for example water, airor steam. The inverted calibration hose 18 walks along the inside of thelining hose 12 and expands and presses its against the inner wall 9 ofthe pipeline 6.

The use of pressurized water (not shown) to invert the calibration hose18 has several benefits. Particularly, the calibration hose 18 is filledwith water gradually so that the calibration hose 18 walks-through thepipeline 6. As the calibration hose 18 is fed into the liner composition12, it can easily travel, as shown in FIG. 1, from a vertical pipelinesection 6 b to a horizontal pipeline section 6 a and vice versa. Thepressurized water makes the inverted calibration hose 18 push againstthe flexible liner composition 12 and forces the liner composition 12outwardly so that it presses against and engages the interior walls 9 ofthe pipeline 6. As a result, the liner composition 12 contacts andconforms to the shape of the internal pipeline walls 9.

The water injected into the calibration hose 18 is heated tosubstantially cure and harden the thermosetting resin. Preferably, thewater is heated to a temperature of at least 100° F. and more preferablyto a temperature of about 130° F. The temperatures can vary depending onthe resin selected for use. The curing reaction is exothermic so thecuring of the resin, itself, generates heat that improves the curingrate. Also, the resin may contain heat-initiated curing agents thataccelerate the curing process. Upon the curing and hardening of theresin, the liner composition 12 becomes attached to the wall surfaces 9inside of the pipeline 6. Preferably, the calibration hose 18 remains inplace for 4-36 hours depending on the epoxies used, the environmentaltemperature and the temperature of the water introduced into thecalibration hose 18 for curing.

The calibration hose 18 can then be removed from the liner composition12 using techniques known in the art. Typically, a rope or cable isattached to the trailing end of the calibration hose 18. An operatorpulls on the rope or cable to remove the calibration hose 18 from theliner composition 12. The resulting composite structure includes a rigidlining hose firmly attached to the pipeline with a rugged, smooth andleak-free sealing inner surface of epoxy material and a highlyreinforced carbon fiber shell.

It can therefore be seen that the present invention provides a highlyreinforced liner composition and method of installing the linercomposition that has not been seen or employed in the prior art. Forthese reasons, the instant invention is believed to represent asignificant advancement in the art, which has substantial commercialmerit.

While there is shown and described herein certain specific structureembodying the invention, it will be manifest to those skilled in the artthat various modifications and rearrangements of the parts may be madewithout departing from the spirit and scope of the underlying inventiveconcept and that the same is not limited to the particular forms hereinshown and described except insofar as indicated by the scope of theappended claims.

What is claimed:
 1. A lining hose for lining an interior surface of anunderground pipeline comprising: an interior layer of non-woven fibrousmaterial; at least one carbon fiber reinforcing layer; exterior layer ofnon-woven fibrous material; a first low viscosity resin initiallywetting out said lining hose; and a second resin having a higherviscosity fully wetting out said lining hose.
 2. The lining hose ofclaim 1, wherein the reinforcing layer further comprises: alternatingplies of reinforcing layers and non-woven fibrous material layers. 3.The lining hose of claim 2, wherein the reinforcing layers, the interiorlayer and the exterior layer are stitched together.
 4. The lining hoseof claim 1, wherein the non-woven fibrous material is apolyester-needled felt.
 5. The lining hose of claim 1, wherein the atleast one reinforcing layer, the interior layer and the exterior layerare stitched together.
 6. The lining hose of claim 1, wherein the lininghose includes an interior layer and an exterior layer of non-wovenfibrous material.
 7. The lining hose of claim 6, wherein the non-wovenfibrous material is a polyester-needled felt.
 8. The lining hose ofclaim 6, wherein the lining hose includes a layer of carbon fiberreinforcing between said interior layer and said exterior layer.
 9. Thelining hose of claim 8, wherein the reinforcing layer, the interiorlayer and the exterior layer are stitched together.
 10. The lining hoseof claim 6, wherein the lining hose includes an interior layer ofnon-woven fibrous material and alternating plies of carbon fiberreinforcing and non-woven fibrous material.
 11. The lining hose of claim10, wherein the reinforcing plies, the interior layer and the non-wovenfibrous material plies are stitched together.